Thyroid nodules are very common. The gold standard for assessing thyroid nodules is fine needle aspiration of the nodules with cytopathological evaluation, which yields a diagnosis of benign or malignant lesion in 70% of cases. However, in 30% of cases, cytopathology will not be sufficient to determine the status of these “indeterminate” lesions. Moreover, indeterminate thyroid lesions on Fine Needle Aspiration (FNA) harbor malignancy in about 25% of cases. Hemi-thyroidectomy or total thyroidectomy has been routinely advocated for definitive diagnosis. But when there is no clear diagnosis it is unclear whether such thyroidectomy is appropriate.
In cancer, microRNAs may function as both tumor suppressors and oncogenes. MicroRNAs have also been used for diagnosis of cancer. See, e.g., Wiemer E A. The role of microRNAs in cancer: no small matter. Eur J Cancer 43:1529-44 (2007); Nikiforova et al. Endocr Pathol 20:85-91 (2009); He et al. Proc Natl Acad Sci USA 102:19075-80 (2005); Pallante et al. Endocr Relat Cancer 17:F91-104 (2010); Sheu et al. Br J Cancer 102:376-82 (2010); Chen et al. Mod Pathol 21:1139-46 (2008); Nikiforova et al. J Clin Endocrinol Metab 93:1600-8 (2008); Pallante et al. Endocr Relat Cancer 13:497-508 (2006); Visone et al. Endocr Relat Cancer 14:791-8 (2007); Weber et al. J Clin Endocrinol Metab 91:3584-91 (2006).
However, many different types of microRNAs exist. Scientists have tried without success to discover which set of markers can accurately stage thyroid lesions regarding their malignant potential. In addition, previous studies have not been able to properly assign a malignant/benign status to thyroid lesions defined as indeterminate by cytological analysis.